The patella - important anatomical relationships

The patella is a bone within a tendon - the tendon of the long quadriceps muscle that spans the region from the hip to the shinbone. The illustration on the right shows one part of the quadriceps muscle (the rectur femoris part) and you can see the patella within its tendon just at the knee joint.

The patella (kneecap) is a 'sesamoid bone'. A sesamoid bone is a bone that develops in a muscle tendon, rather than being attached by ligaments to another bone. The tendon in which the patella develops is the tendon of the quadriceps muscle, the big muscle that makes up the bulk of your 'lap'.